Convert some ObjC msgSends to runtime calls.

It is faster to directly call the ObjC runtime for methods such as retain/release instead of sending a message to those functions.

This patch adds support for converting messages to retain/release/alloc/autorelease to their equivalent runtime calls.

Tests included for the positive case of applying this transformation, negative tests that we ensure we only convert "alloc" to objc_alloc, not "alloc2", and also a driver test to ensure we enable this only for supported runtime versions.

Reviewed by John McCall.

Differential Revision: http://reviews.llvm.org/D14737

llvm-svn: 263607

1 files changed, 12 insertions, 0 deletions

diff --git a/clang/lib/Driver/Tools.cpp b/clang/lib/Driver/Tools.cpp
index cb398711631..2849d513df7 100644
--- a/clang/lib/Driver/Tools.cpp
+++ b/clang/lib/Driver/Tools.cpp
@@ -5284,6 +5284,18 @@ void Clang::ConstructJob(Compilation &C, const JobAction &JA,
 
   }
 
+  // Allow the user to control whether messages can be converted to runtime
+  // functions.
+  if (types::isObjC(InputType)) {
+    auto *Arg = Args.getLastArg(
+        options::OPT_fobjc_convert_messages_to_runtime_calls,
+        options::OPT_fno_objc_convert_messages_to_runtime_calls);
+    if (Arg &&
+        Arg->getOption().matches(
+            options::OPT_fno_objc_convert_messages_to_runtime_calls))
+      CmdArgs.push_back("-fno-objc-convert-messages-to-runtime-calls");
+  }
+
   // -fobjc-infer-related-result-type is the default, except in the Objective-C
   // rewriter.
   if (rewriteKind != RK_None)